Experimental Study On The Effect Of Carbon Nanoparticles Injection On Rat Hepatic Tumor Resection Margin And Lymph Tracing

Objective: This experiment aims to build two hepatic tumor rat models of different growth patterns and apply carbon nanoparticles injection to two hepatic tumor operation models for the purpose of studying the value of carbon nanoparticles injection tracing for liver cancer operation, researching the effect of carbon nanoparticles injection on hepatic tumor resection margin and lymph tracing, and exploring for new methods to improve the clinical treatment of liver cancer.Methods: Walker₂56 cell strains (from rat breast cancer cells) are used to prepare, respectively in Planting Method and Injection Method, two kinds of hepatic tumor rat models, i.e. tumor expansive growth and infiltrating growth model, to simulate clinical human liver cancer. The theoretical value of parenchymal hepatic resection rate (PHRR) is used as reference for resection margin standards in hepatic tumor rat model. The two models are respectively provided with an experimental group and a control group, each with 30 samples. The operations for the experimental group are provided with in-tumor injection of carbon nanoparticles injection for tracing while those for the control group are traditional ones. Observe the tumor and lymph tracing effect in the experimental group. Cut the tumors, dissect local lymph nodes and then get samples in both the experimental group and control group. Measure the minimum length of resection margin in each sample and record the number, size and position of lymph node dissected. Carry out pathological examination for the samples, observe the margins of the tumors and normal liver tissues around the tumor, search for tumor cells within 1mm from the margins of tumors, and then record the number of tumor positive on resection margin. Finally, carry out statistical analysis on the data on the experimental group and control group in both models.Results: After being injected into the rat hepatic tumor, carbon nanoparticles injection can infiltrate to the normal liver tissue beyond the tumor margin. Within 8min after injection, a visible black belt, with a width of 3 to 5mm or so, will appear on the margin of the hepatic tumor and the tumor-related lymph vessel in the tissues around the tumor will be blacked. After 10min, the drainage lymph vessels outside of the liver, as well as local lymph nodes, are gradually blacked. After 30min, blacking in lymph tissue is basically stable and has no marked change.1 Comparative results of resection margin in the experimental group and control group in expansive growth modelThe minimum resection margin in the experimental group is 4.007±0.1799mm and that in the control group is 4.003±0.2918mm. The two independent sample t test shows the p value is >0.05, indicating no statistical significant difference. So it can be deemed that the two groups in expansive growth model have no difference in minimum resection margin length. The tumor positive rate within 1mm from resection margin is 0% in both groups, the reason of which may be no micro-transfer of tumor and no vein tumor thrombi due to the short period of tumor forming (about 14d).2 Comparative results of resection margin in the experimental group and control group in infiltrating growth modelThe minimum resection margin in the experimental group is 4.083±0.1577mm and that in the control group is 3.777±0.2542mm. The two independent sample t test shows the p value is <0.05, indicating a statistical significant difference. So it can be deemed that the two groups in infiltrating growth model have a difference in minimum resection margin length. Among the 30 samples in experimental group, 7 samples are found to have residual tumor cells within 0.1mm from the resection margin, representing a tumor positive rate of 23.33%(7/30). Among the 30 sample in control group, 16 ones are found to have residual tumor cells within 1mm from the resection margin, representing a tumor positive rate of 53.33%(16/30). Using Fisher's Exact Test to analyze the difference in tumor positive rate between the experimental group and control group, the p value is <0.05, indicating a statistical significant difference. So it can be deemed that the two groups in infiltrating model have a difference in tumor positive rate.3 Comparative results of lymph node dissection in the experimental group and control group in expansive growth modelThe total number of dissected lymph nodes in the experimental group is 457, averagely 15.23±1.382 in each sample. The total number of dissected lymph nodes in the control group is 311, averagely 10.37±1.299 in each sample. The two independent sample t test shows the p value is <0.05, indicating a statistical significant difference. So it can be deemed that the two groups in expansive growth model have a difference in the number of dissected lymph nodes.Among the dissected lymph nodes in the experimental group, 97 ones have a diameter of less than 1mm, taking 21.23%; 309 ones have a diameter of 1mm to 2mm, taking 67.61%; 51 ones have a diameter of more than 2mm, taking 11.16%. Among the dissected lymph nodes in the control group, 44 ones have a diameter of less than 1mm, taking 14.15%; 219 ones have a diameter of 1mm to 2mm, taking 70.42%; 48 ones have a diameter of more than 2mm, taking 15.43%. Usingχ2 test, the p value is <0.05, indicating a statistical significant difference. So it can be deemed that the two groups in expansive growth model have a difference in composition structure of dissected lymph node numbers. As for the distances among lymph nodes, in the experimental group there are 159 nodes with short distance from the nearby ones, taking 34.79%, 215 ones with medium distance, taking 47.05%, and 83 ones with long distance, taking 18.16%. In the control group, there are 108 ones with short distance, taking 34.73%, 144 ones with medium distance, taking 46.30%, and 59 ones with long distance, taking 18.97%. Usingχ² test, the p value is >0.05, indicating no statistical significant difference. So it can be deemed that two groups in expansive growth model have no difference in composition structure of position of dissected lymph nodes.4 Comparative results of lymph node dissection in the experimental group and control group in infiltrating growth modelThe total number of dissected lymph nodes in the experimental group is 459, averagely 15.30±1.343 in each sample. The total number of dissected lymph nodes in the control group is 308, averagely 10.27±1.230 in each sample. The two independent sample t test shows the p value is <0.05, indicating a statistical significant difference. So it can be deemed that the two groups in infiltrating growth model have a difference in the number of dissected lymph nodes.Among the dissected lymph nodes in the experimental group, 102 ones have a diameter of less than 1mm, taking 22.22%; 303 ones have a diameter of 1mm to 2mm, taking 66.01%; 54 ones have a diameter of more than 2mm, taking 11.76%. Among the dissected lymph nodes in the control group, 44 ones have a diameter of less than 1mm, taking 13.31%; 223 ones have a diameter of 1mm to 2mm, taking 72.40%; 44 ones have a diameter of more than 2mm, taking 14.29%. Usingχ² test, the p value is <0.05, indicating a statistical significant difference. So it can be deemed that the two groups in infiltrating growth model have a difference in composition structure of dissected lymph node numbers. As for the distances among lymph nodes, in the experimental group there are 162 nodes with short distance from the nearby ones, taking 35.29%, 210 ones with medium distance, taking 45.75%, and 87 ones with long distance, taking 18.95%. In the control group, there are 103 ones with short distance, taking 33.44%, 139 ones with medium distance, taking 45.13%, and 66 ones with long distance, taking 21.43%. Usingχ² test, the p value is >0.05, indicating no statistical significant difference. So it can be deemed that two groups in infiltrating growth model have no difference in composition structure of position of dissected lymph nodes.Conclusion: The experiment results demonstrate the obvious tracing effect of carbon nanoparticles injection on tumor and lymph in hepatic tumor rat models. Application of carbon nanoparticles injection can improve the visibility of the tumor resection margin for operators, so that the blindness in determining the resection margin in traditional operation can be avoided and the tumor positive rate on resection margin can be effectively reduced. Beside, carbon nanoparticles injection can also black the drainage lymph nodes in tumor area, making the lymph node dissection in operation more complete, more rapid and safer, and helping to reduce complexity and danger in lymph node dissection, as well as the post-operation recrudescence and transfer rate of liver cancer.